Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=fce8c41c9f68b9af36f3076bae8f1d469a6e7aab
Commit: fce8c41c9f68b9af36f3076bae8f1d469a6e7aab
Parent: 0983a88b9f0ceffb2116ce92c7b273ce2aec7b93
Author: Jeff Dike <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 4 22:31:09 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Feb 5 09:44:29 2008 -0800
uml: use barrier() instead of mb()
signals_enabled and pending have requirements on the order in which they are
modified. This used to be done by declaring them volatile and putting an
mb()
where the ordering requirements were in effect.
After getting a better (I hope) understanding of how to do this correctly,
the
volatile declarations are gone and the mb()'s replaced by barrier()'s.
One of the mb()'s was deleted because I see no problematic writes that could
be re-ordered past that point.
Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
arch/um/os-Linux/signal.c | 28 ++++++++--------------------
1 files changed, 8 insertions(+), 20 deletions(-)
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 7ff8f57..62a66f3 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -15,6 +15,9 @@
#include "sysdep/sigcontext.h"
#include "user.h"
+/* Copied from linux/compiler-gcc.h since we can't include it directly */
+#define barrier() __asm__ __volatile__("": : :"memory")
+
/*
* These are the asynchronous signals. SIGPROF is excluded because we want to
* be able to profile all of UML, not just the non-critical sections. If
@@ -27,13 +30,8 @@
#define SIGVTALRM_BIT 1
#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
-/*
- * These are used by both the signal handlers and
- * block/unblock_signals. I don't want modifications cached in a
- * register - they must go straight to memory.
- */
-static volatile int signals_enabled = 1;
-static volatile int pending = 0;
+static int signals_enabled;
+static unsigned int pending;
void sig_handler(int sig, struct sigcontext *sc)
{
@@ -198,7 +196,7 @@ void block_signals(void)
* This might matter if gcc figures out how to inline this and
* decides to shuffle this code into the caller.
*/
- mb();
+ barrier();
}
void unblock_signals(void)
@@ -224,21 +222,11 @@ void unblock_signals(void)
* Setting signals_enabled and reading pending must
* happen in this order.
*/
- mb();
+ barrier();
save_pending = pending;
- if (save_pending == 0) {
- /*
- * This must return with signals enabled, so
- * this barrier ensures that writes are
- * flushed out before the return. This might
- * matter if gcc figures out how to inline
- * this (unlikely, given its size) and decides
- * to shuffle this code into the caller.
- */
- mb();
+ if (save_pending == 0)
return;
- }
pending = 0;
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
